using System;

public class Program

{

    public static void Main()

    {

        var sum = 0.0;

        for (int x = 1; x <= 30; x++)

        {

            sum += (2 * x - 3) / (Math.Pow(x, 3) - 2);

        }

        Console.WriteLine($"Sum = {sum}");

    }

}